Apparatus for the rapid removal of brine from mercury cells



Dec. 26, 1967 J, SZECHTMAN APPARATUS FOR THE RAPID REMOVAL OF BRINE-FROM MERCURY CELLS 2 Sheets-Sheet l Original Filed Dec. 17, 1959 mum.

' INVENTOR; JOSHUA SZECHTMAN Dec. 26, 1967 J. SZECHTMAN APPARATUS FORTHE RAPID REMOVAL.- OF BRINE FROM MERCURY CELLS 2 Sheets-Sheet 2Original Filed Dec.

INVENTOR. Jo SHUA Sz ECH'TMA/V BYWYQZQ// ATTORNEY,

United States Patent 7 Claims. or. 204-219 This application is adivision of application Ser. No. 860,294, filed Dec. 17, 1959 which inturn is a continuation-in-part of application Ser. No. 611,980 filedSept. 25, 1956, both now abandoned.

This invention relates to electrolytic mercury cells and methods foroperating the same and is particularly concerned with the control of thelevel of brine within such cells for rapid removal of such brine whendesired.

Cells of the kind here under consideration and methods of operating thesame wherein chlorine is produced from brine with a mobile mercurycathode below the brine, and with anodes extending into the brine,always have a considerable amount of chlorine gas present in them whilethey are in operation. This chlorine gas contains moisture making itvery corrosive to metals and many other materials. Also, during theoperation of the cell, the layer of sodium chloride brine is permeatedwith chlorine gas but that gas cannot attack the mercury of the cathodedue to the electro-chemical forces which drive the chlorine upwardlyaway from the mercury. When the operation of the cell is stopped,however, there is a substantial period of time during which nothingstands in the way of the chlorine in the brine attacking the mercury,or, when the mercury is removed, attacking the then exposed steel partsof the cell bottom.

In prior art cells, when the operation of the cell is stopped, the layerof brine is trapped inside and cannot be removed until the cell isopened. This opening must be delayed until the chlorine gas accumulatedabove the layer of brine has been evacuated. Then the manner in whichthe cell can be opened is dictated by the necessity of providing properprotection of the operating personnel and surrounding equipment. Also,the method followed in the stopping or shutting down cells in accordancewith prior practices required the presence of costly short circuitswitch equipment to make sure that the cell was clearly cut out of thecircuit and no current could run through it.

The prior art factors all dictated a design of cell that could not beopened at a moments notice. Furthermore, such factors, as well as theneed tomaintain a certain level of brine in the cell and the need tosafeguard against costly mercury losses through leaks, have dictateddesigns of mercury cells that would not permit any speedy evacuation ofchlorine laden brine. Generally speaking, once you start the operationof a prior art mercury cell of the type here considered, you cant stopit, at least without considerable damage being done to the cell, or lossof mercury, or both.

The invention eliminates the foregoing and other drawbacks of prior artcell constructions and methods of operation and, in fact, converts themercury cell into a form of apparatus that can be started up and stoppedeach day if one wishes. It does this by providing methods and means forthe speedy evacuation of the brine from the cell, once its operation isstopped while retaining all of the necessary safety features for thecell. The method and apparatus provides for evacuation of the brinewithout opening the cell, so the chlorine may be safely removed and thebrine drawn off without exposing the operating personnel to possibleinjury and without having the merthe end 26 of the wall 22 and is turneddown at 27 beneath Patented Dec. 26, 1967 'ice no necessity forexpensive short-circuit equipment for by passing the cell.

It is accordingly an object of this invention to provide methods andapparatus for the stopping of the operation of mercury cells withoutlaying the cells open to injury.

Another object is to protect the mercury cathode in electrolytic cellsfrom attack by the chlorine once the action of the cell is stopped.

Another object is to effect the foregoing stoppage without opening thecell.

Still another object is to eliminate costly short-circuit equipment forthe by passing of current by the cell.

A more specific object is to provide for the speedy evacuation of brinefrom a mercury cell whose action has been stopped.

A still further object is to provide for maintaining the evacuatingmeans ineffective during the operation of the cell.

Further and more detailed objects will partly be obvious and will partlybe pointed out as the description of the invention taken inconjunctionwith the accompanying drawing proceeds.

In the drawing:

FIG. 1 is a fragmentary vertical section of a portion of an electrolyticmercury cell in accordance with the invention and for carrying out themethod of the same.

FIG. 2 is a view greatly enlarged of a portion of the cell carrying thepresently preferred form of brine control means, for the carrying out ofthe method and showing such means in closed position; and

FIG. 3 is a similar view showing such means in open position.

In mercury cells of the type here contemplated, the primary cell inwhich the brine is decomposed is normally in the form of a channelmember, generally indicated at 1, providing an inclined base 2 overwhose upper surface a layer of mercury 3 flows, the flow being to theright as viewed in FIG. 1. The incline here is exaggerated for thepurpose of emphasis. This mercury serves as the cathode for thedecomposition of the layer of brine 4. Anodes 5 are properly positionedin the brine and in relation to the mercury layer 3 and are properlyconnected to a suitable source of electric current by means of theirstems 6 and a bus bar 7.

At the end 8 of such cells they usually carry an outlet housingproviding for the outlet of the brine and a means for the outlet of themercury with a suitable trap in between so that none of the brine getsto the mercury outlet compartment. As here shown, there is a trap 9providing for a water seal 11 above the mercury 12 flowing from thebrine outlet chamber. The subsequent flushing chamber 10 has a furtherwater seal 13 over the mercury therein and has a suitably formedflushing device 14 pivoted at 15 so that it may be swung to the left toenable the gate portion 16 to be moved away from its side 17 and allowthe mercury to be flushed out through the flush tube 18. The tube 19provides the water inlet for supplying water 13 over the mercury. Asimilar tube introduces water into the trap 9 through the opening 20.

The trap 9 has a removable cover 21 and has side walls 22 and 23. Theside walls 22 and 23 extend transversely across the outlet housing ofthe cell, the bottom wall 24 of which is recessed in a transversechannel 25 lying beneaththe end 28 of the Wall 23. These ends anddownturned portions serve-as part of the trapping to prevent any brineand chlorine gas from get-ting into the chambers 9 and 10.

The wall'23 forms theend wall of the brine outlet chamber 31 which is nomore than a clear continuation of the interior 36 of the cell. In otherwords there is no trap or other interruption between the normal interior36 of the cell and the chamber 31. This chamber has a top plate 32bolted in gas tight engagement to the end of the cover 30 at one sideand to the inturned upper end of the wall member 23 at its other side.When properly secured in place the plate 32 positively contain-s thechlorine gas which collects over the brine. Nevertheless it may beremoved for removal and adjustment of the brine level control anddumping means when needed. The cover 30 is secured and tightly fixed inplace over the cell interior or through 36, preferably with a pluralityof fastenings so that it is necessary to disassemble the cell in orderto remove it.

The flanged end 23 of the bottom wall 24 lies in opposition to the end 8of the cell body and is suitably bolted thereto, as shown at 34, withsuitable gasketing means 35 therebetween in order to assure a leakproofjoint.

Cells as heretofore devised provided means for taking off brine depletedthrough an overflow pipe whose open top was just below the surface ofthe brine in the end chamber. This was a fixed structure, however, andthe cover over the chamber was a solid imperforate piece. Thus to removeany brine in excess of the small overflow continually running off, onehad first to remove the cover. To do this the cell would have to be shutdown, the electric current shut off and short circuited and as much freechlorine as possible in the space above the brine layer in the cellwould be removed by vacuum action. As soon as the electric current wasshut off, however, a certain amount of the chlorine gas would be takenback into the brine, creating a mixture of chlorine and brine. Thismixture would so damage the cell through corrosive action while thecover was being removed, that the cell could not be started up again, atleast without material reconditioning. Hence, the general understandingin the prior art has been that once one of these cells was started upyou couldnt stop it. The cell and method of operation of the same inaccordance with the invention, on the contrary, enable the starting andstopping each day if desired.

Considering the apparatus here disclosed for enabling the method of theinvention to be carried out, it is to be noted that a portion of thebottom wall 24 of the outlet housing within the brine outlet chamber 31has an annular lip 40 formed upwardly therefrom to surround a dischargeopening 41. This discharge opening is bordered by a downwardly extendingshort pipe section 42, to which is secured the runoff conduit 43 for thebrine. It will be noted that the lip 40 is rounded over on its uppersurface, as seen at 44 and that the mouth of the opening 41 is tapereddownwardly and inwardly at 45, all of which is best seen in FIG. 3.

Therounded over top 44 of the lip 40 is formed upwardly to lie justabove the upper surface 46 of the stream of mercury 3 flowing past.Thus, when the conduit is open, as seen in FIG. 3, practically all ofthe brine 4 can run out through that conduit. None of the mercury willescape therethrough due to the resistance resulting from its weightagainst any action of the brine to draw it along.

Under normal operating conditions, however, the level of the brine inthe cell and hence in the outlet compartment 31 will need to be well upwithin the cell and in the compartment, with only the spent portionclose to the top brine surface being allowed to run off. The inventionprovides for that run-off and, in addition, provides for theinstantaneous full opening of the discharge opening 41 so thatpractically all of the brine in the cell can be quickly dumped.

This control is achieved by the multiple weighted valve member shown indetail in FIGS. 2 and 3 and consisting generally of a lower closing tube50, an upper overflow tube 51, a weighted ring 52 and a mounting andlifting spider for the tubes and ring, generally indicated at 53. Thespider 53 is carried by a shaft 54 which extends up through an opening55 in the cover 30.

Coming back to the details of this valve arrangement, it is first seenthat the lower portion of the tube 50 is tapered inwardly at 56 and itsouter surface is given a taper 57 mating with the taper 45 at the mouthof the opening 41. Thus, as seen in FIG. 2, when these are broughttogether a liquid tight joint is formed and that would be their normalposition.

The upper portion of the tube 50 is of cylindrical formation, is screwthreaded on its exterior surface at 58 for the threaded reception of thelower portion 59 of the tube 51. Both of these are threaded tosufiicient extent to permit them to be adjusted one with respect to theother so that the overflow level provided by the upper end 60 of thetube 51 can be set at the desired height.

The upper portion of the tube 51 is exteriorly screw threaded for thethreaded reception of the hold down ring 52. This ring, of substantialweight, assists in holding the valve construction down so that thesurface 57 will remain in tight engagement with the surface 45 duringthe normal operation of the cell. Also, the ring is here used as thelifting means to be engaged by the arms 61 of the spider 53. As hereshown, those arms 61 are four in number, extend down past the outersurface of the ring 52, and are turned in beneath the same as shown at62. Furthermore, if desired, the spider may be formed with a retainingring 63, L-shaped in cross section, whose vertical portion is secured tothe inner surface of the fingers 61 with its bottom horizontal surfaceseating down on the ring 52 to hold the spider in fixed position withrespect to the ring. From what has been said, it will be apparent thatthis structure will serve the purpose of maintaining the opening 41closed under normal operation conditions, merely permitting a certainoverflow of spent brine down through the tubes into the runoff pipe 42,as illustrated in FIG. 2. When, however, it is desired to quickly dumpthe brine in the cell, that is achieved by raising the tube 50 so thatits seat 57 disengages from the seat 45 and the whole of the opening isexposed for the runoff of the brine.

It is essential, however, that in the normal operation of the cell therebe no opening in the cover 30 from which chlorine could escape into theatmosphere. This is taken care of by the provision of a diaphragm typeof rubber sleeve, generally indicated at 64. This sleeve is providedwith a laterally extending base portion 65 held down against the uppersurface of the cover 30 in leak tight engagement therewith by means ofan annular metal retaining ring 66 lying within the enlarged borderinghead 67 of the base portion 65. The ring 66 is held down by a pluralityof bolts 68 passing therethrough and through the laterally extendingportion 65 and secured in the cover 30.

The intermediate portion of the diaphragm member 64 is normally belliedout at 69 in a readily flexible body portion. The upper end of themember 64 is contracted into a collar portion 70 of an internal diameterto snugly receive the outer surface of the shaft 54. The collar portion70 is tightly clamped against that outer surface by some suitable means,such as the clamping ring 71 here shown. It will be apparent from thefore-going, that though the opening 55 provides easy egress for chlorinegas, since it is sufliciently larger than the shaft 54 to permit forfree movement of that shaft, any such gas will be contained by themember 64 and the securement thereof and cannot leak out to theatmosphere. That member is, of course, made of suitable rubberlikematerial properly resistant to the action of the chlorine. It issuflicientliy pliable that it will yield under the weight of the valveconstruction with its midportion extending outwardly into a ring shape,as seen in FIG. 2, to permit the surface 57 to effectively seat againstthe surface 45,

Any suitable means for raising the valve member from the FIG. 2 positionto that of FIG. 3 may be provided. It should, however, be one whichworks freely and easily. As here illustrated the raising is etfected bythe vertical slotting of the upper end of the valve stem 54 from theposition 72 upward to the end 73. The slot has a roller 74 mountedtherein by means of a transverse pin 75. This roller is engaged by onearm 76 of a lever-like operating member, which is pivoted at 77 aboutsubstantially its mid-point in the slotted upper end of a stanchion 78with the other end 79 of the operating member extending out from theother side of the pivot 77. The stanchion 78 is suitably mounted on thecover 30 by means of a base plate 80 secured by a plurality of bolts 81.

To carry out the method of the invention utilizing the apparatus hereillustrated the cell is set to 'be put into operation by first settingthe members 50 and 51 with respect to each other so that the overflowend 60 will be at a desired position for the proper amount of .overflowwhile the surfaces 57 and 45 are seated together to form a leakproofjoint. The valve member will then have the position illustrated in FIGS.1 and 2. The mobile mercury cathode is caused to flow, the brine isintroduced on top of it to the desired depth and the electric current isturned on. The brine is decomposed giving olf chlorine gas while thealkali, such as sodium forms an amalgam with the mercury. Caustic sodais also formed. The chlorine gas is taken off from above the brine. Thebrine is continuously replenished and spent brine runs off byoverflowing the surface 60 as seen in FIGS. 2 and 3, So long as thecurrent is kept on chlorine will flow away from the brine but once thecurrent is cut off the chlorine still present tends to be reabsorbed bythe brine making a very corrosive mixture. The method of the inventionprevents this from happening and, at the same time, eliminates theelectrical path through the cell.

According to the method of the invention when it is desired to stop theoperation of the cell, the current is cut off and almost simultaneouslythe handle 79 is pressed down, thereby raising the stern of the shaft 54and bringing the valve member 50 off its seat. This quickly dumps all ofthe brine from the cell through the conduit 43-, possibly leaving just alittle on top of the mercury in the compartment 31 for subsequentdraining. The slope on which the cell is set and operates assures thatany brine left will be such small amount as may be left in thecompartment 31 after the dumping of the brine has been completed. Thusthe brine from the cell and any chlorine contained therein is removed sorapidly that corrosive action .on the cell is practically eliminated.There is no need to Wait until the chlorine gas is removed and the cellis opened. As soon as the brine level falls below the lower surfaces ofthe anodes 5 no current can flow so no short circuiting of the cell isneeded. Best of all the cell is undamaged and can be started up againwithout opening and whenever desired merely by letting the valve member50 return to its closed position, reintroducing mercury and brine andturning on the current.

Effective reclosing of the valve 45-56 is assured by virtue of theweight of the valve member itself enhanced by the substantial additionalweight of the ring 52. As previously pointed out, the ring 52 is ofsubstantial weight and serves to assure that the tapered surfaces 45 and57 will remain in liquid tight engagement once they are seated togetherand the cell is in operation. Thus, the method of operating and stoppingelectrolytic cells in accordance with the invention converts them fromsomething that can be started and not stopped into apparatus which canbe stopped and restarted as desired.

In the foregoing description and accompanying drawing the method of theinvention has been illustrated as being carried out by the use of oneparticular form of dump valve. It is, of course, to be understood,however, that such showing is merely for illustrative and not limitingpurposes and that alternatives thereof and variations therein as wouldsuggest themselves to those skilled in the art can be employed withoutdeparting from the spirit and scope of the invention. Speaking moregenerally, since certain changes in the method of operation and in theconstruction set forth may be made without departing from the scope ofthe invention, it is intended that all matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted asillustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secureby Letters Patent is: v

1. Apparatus for the rapid removal of brine from mercury cellscomprising a cell and a chamber member secured to the outlet endthereof, enclosing means for sealing said cell and chamber from theatmosphere, the interior ,of said chamber forming an uninterruptedcontinuation of the interior of said cell and being formed with meansfor maintaining a stream of mercury therein at a predetermined level, adischarge conduit connected to the bottom of said chamber for theremoval of the brine from the cell, said conduit having an opening withinward and downward taper and having a rounded lip adjacent saidpredetermined mercury level, a tubular valve extending to apredetermined brine level which is maintained during operation of thecell and having an inward and downward taper for sealing fit and seatedin said opening and normally closed for retaining the brine in the cell,and means for opening the valve quickly to discharge the brine rapidlyfrom the cell and chamber while retaining the sealing of said cell andchamber from the atmosphere, said means for opening the valve includinga manually operable handle exterior to the enclosing means, and flexiblemeans secured to a portion of said valve stem and said enclosing meansto permit the operation of the valve without permitting the escape ofgas from said cell.

2. Apparatus as set forth in claim 1 wherein said valve includestelescoping members for axial adjustment of the valve seat.

3. Apparatus as set forth in claim 2 wherein said valve includes weightmembers for urging the valve to remain in its closed position.

4. In electrolytic mercury cell construction, an elongated hollow sealedcell member and a sealed chamber member joined to the outlet end of saidcell member and having its interior forming an uninterrupted extensionof the interior of said cell member and being provided with means formaintaining a stream of mercury therein at a predetermined level withbrine to to be electrolyzed ove'rlying said mercury, a dischargedconduit connected to the bottom of said chamber member for the rapidremoval of the brine from said members without removing the mercury frombelow it, said conduit having an opening with an inward and downwardtaper and having a rounded lip adjacent to the bottom level of the brinebut above said level of the mercury, a valve having an inward anddownward taper for sealing fit and seated in said opening and normallyclosing said opening for retaining the brine in said cell, means foropening said valve to rapidly discharge the brine while maintaining saidmembers in sealed relationship with respect to the atmosphere, saidvalve opening means including a valve stem which extends exteriorly ofsaid members, and flexible sealing means secured to a portion of saidvalve stem and to the top of said chamber member providing for the fulloperation of said valve while preventing the escape of gas from saidmembers.

5. Apparatus as set forth in claim 4 wherein in addition the valve istubular and extends to a predetermined brine level such that excessbrine overflows through the tube and conduit and out of the cell.

6. Apparatus as set forth in claim 5 wherein the overflow opening of thetubular valve is adjustable in height to predetermine the brine level inthe cell.

7. Apparatus as set forth in claim 6 wherein the valve includes thecombination of the valve stem connected to a tubular member inside thechamber so that the tubular member is open at a predetermined brinelevel and the seating portion of the valve is in threaded connectionwith the tubular member, the combination of the tubular 7 8 member and.seating pgxtion forming telescoping FOREIGN PATENTS m m ers- ReferencesCited 411,385 8/1945 Italy.

UNITED STATES PATENTS 5 JOHN H. MACK, Primary Examiner. 320,950 6/1885McHugh 4-61 Gl S. Examiner.

1. APPARATUS FOR THE RAPID REMOVAL OF BRINE FROM MERCURY CELLSCOMPRISING A CELL AND A CHAMBER MEMBER SECURED TO THE OUTLET ENDTHEREOF, ENCLOSING MEANS FOR SEALING SAID CELL AND CHAMBER FROM THEATMOSPHERE, THE INTERIOR OF SAID CHAMBER FORMING AN UNINTERRUPEDCONTINUATION OF THE INTERIOR OF SAID CELL AND BEING FORMED WITH MEANSFOR MAINTAINING A STREAM OF MERCUY THEREIN AT A PREDETERMINED LEVEL, ADISCHARGE CONDUUITE CONNECTED TO THE BOTTOM OF SAID CHAMBER FOR THEREMOVAL OF THE BRINE FROM THE CELL, SAID CONDUIT HAVING AN OPENING WITHINWARD AND DOWNWARD TAPER AND HAVING AROUNDED LIP ADJACENT SAIDPREDETERMINED MERCURY LEVEL, A TUBULAR VALVE EXTENDING TO APREDETERMINED BRINE LEVEL WHICH IS MAINTAINED DURING OPERATION OF THECELL AN DHAVING AN INWARD AND DOWNWARD TAPER FOR SEALING FIT AND SEATEDIN SAID OPENING AND NORMALALY CLOSED FOR RETAINING THE BRINE IN THECELL, AND MEANS FOR OPENING THE VALVE QUICKLY TO DISCHARGE THE BRINERAPIDLY FROM THE CELL AND CHAMBER WHILE RETAINING TH SEALING OF SAIDCELL AND CHAMBER FROM THE ATMOSPHERE, SAID MEANS FOR OPENING THE VALVEINCLUDING A MANUALLY OPERABLE HANDLE EXTERIOR TO THE ENCLOSING MEANS,AND FLEXIBLE MEANS SECURED TO A PORTION OF SAID VALVE STEM AND SAIDENCLOSING MEANS TO PERMIT THE OPERATION OF THE VALVE WITHOUT PERMITTINGTHE ESCAPE OF GAS FROM SAID CELL.